Handgrenade.

Can be printed (upside down) in TPU without supports (I used 95A TPU with 5% gyroid infill)

Using flexible filament, provides a part that is much more durable and less painful when impacting on humans.

Could even be used as a stress ball, if it is printed satisfyingly malleable.

Just print in one pice. But if needed, the model can be split into parts/objects (e.g. in Prusaslicer). Then the handle and body of the grenade can be printed separately in different colours.